A reactor is a passive element using, e.g., windings with intent to introduce reactance in a circuit. The reactor is used in various electronic circuits and electric circuits, etc. for, e.g., preventing harmonic currents in a power-factor improvement circuit, smoothing current pulsations in a current type inverter and chopper control, and boosting a DC voltage in a converter. Further, in the electric power system, the reactor is used as, e.g., a shunt reactor for compensating for a phase-advanced reactive current and boosting a receiving-end voltage, a serial reactor (current limiting reactor) for increasing impedance in the system to reduce the short-circuit capacity, and a arc suppression coil (neutral reactor) for distinguishing a fault current generated in the event of a one-line ground fault.
The reactor includes a coil and an iron core (core member) serving as a path for magnetic flux that is generated when electric power is supplied to the coil. The iron core is fabricated, for example, by layering magnetic steel sheets in the circumferential direction as an integral unit to form a disk-shaped block iron core (also called an iron core packet, a radial block iron core, or a radial core), and by stacking the plurality of disk-shaped block iron cores in the axial direction (see, e.g., Patent Literature (PTL) 1, PTL 2, and PTL 3). More specifically, for example, a cylindrical block iron core is fabricated by successively layering thin iron sheets with different widths to form a sub-block, which has the shape of a sector in section, and by arranging the plurality of sub-blocks in a circular form (see, e.g., PTL 3).
Additionally, the reactor is a device to introduce reactance in a circuit, as described above, and it basically includes one winding per phase. On the other hand, a transformer includes two or more windings per phase and differs from the reactor.
With the related-art reactor, however, because the block iron core is manufactured, as described above, by successively layering thin iron sheets with different widths to form a sub-block, which has the shape of a sector in section, and by arranging the plurality of sub-blocks in a circular form, more man-hours have been required to manufacture the reactor and a cost reduction of the reactor has been difficult to realize.